Electro-optical device and electronic device

Abstract

An electro-optical device includes a temperature detecting element and an electrostatic protection circuit configured to protect the temperature detecting element from a surge current. The electrostatic protection circuit includes a transistor electrically connected to the temperature detecting element in parallel, a first capacitance element electrically connected to the transistor, and a resistance element electrically connected to the first capacitance element in parallel. The electrostatic capacity of the first capacitance element is greater than a gate capacity between a gate electrode and a semiconductor layer that constitutes the transistor. In addition, a dielectric layer of the first capacitance element is thicker than a gate insulating film of the transistor.

What is claimed is: 
     
       1. An electro-optical device comprising:
 a temperature detecting element; and 
 an electrostatic protection circuit includes: 
 a transistor including a gate electrode, a semiconductor layer, and a gate insulating film provided between the semiconductor layer and the gate electrode, the transistor being electrically connected in parallel to the temperature detecting element; 
 a first capacitance element including a first capacitance electrode, a second capacitance electrode, and a first dielectric layer provided between the first capacitance electrode and the second capacitance electrode, the first capacitance element being electrically connected to the transistor; and 
 a resistance element having one end electrically connected to the gate electrode and the first capacitance electrode and having another end electrically connected to the second capacitance electrode and a source-drain region on one side of the semiconductor layer, wherein 
 an electrostatic capacity of the first capacitance element is greater than an electrostatic capacity between the gate electrode and the semiconductor layer. 
 
     
     
       2. The electro-optical device according to  claim 1 , wherein
 a thickness of the first dielectric layer is greater than a thickness of the gate insulating film. 
 
     
     
       3. The electro-optical device according to  claim 1 , wherein the first capacitance element includes:
 a third capacitance electrode electrically connected to the second capacitance electrode, 
 a fourth capacitance electrode electrically connected to the first capacitance electrode, and 
 a second dielectric layer provided between the third capacitance electrode and the fourth capacitance electrode, and 
 a thickness of the first dielectric layer and a thickness of the second dielectric layer are each greater than a thickness of the gate insulating film. 
 
     
     
       4. The electro-optical device according to  claim 3 , wherein
 the first capacitance electrode, the second capacitance electrode, the third capacitance electrode, and the fourth capacitance electrode at least partially overlap with each other in plan view. 
 
     
     
       5. The electro-optical device according to  claim 3 , wherein
 the second capacitance electrode and the third capacitance electrode are formed of an electrically conducting integral film. 
 
     
     
       6. The electro-optical device according to  claim 1 , wherein
 a thickness of an insulating film provided between the first capacitance electrode and the second capacitance electrode is greater in a peripheral area of the insulating film that overlaps with an end portion of the first capacitance electrode and an end portion of the second capacitance electrode in plan view than in an area, inside the peripheral area, where the first capacitance electrode and the second capacitance electrode overlap in plan view. 
 
     
     
       7. The electro-optical device according to  claim 1 , comprising:
 a second capacitance element electrically connected in series to the first capacitance element, wherein 
 the second capacitance element includes: 
 a fifth capacitance electrode electrically connected to the first capacitance electrode; 
 a sixth capacitance electrode electrically connected to a source-drain region on another side of the semiconductor layer; and 
 a third dielectric layer provided between the fifth capacitance electrode and the sixth capacitance electrode. 
 
     
     
       8. The electro-optical device according to  claim 1 , wherein
 the transistor includes a plurality of unit transistor elements electrically connected in parallel. 
 
     
     
       9. The electro-optical device according to  claim 1 , comprising:
 a display region in which a plurality of pixels each including a pixel electrode and a retention capacitor are arrayed, wherein 
 the retention capacitor includes: 
 a first electrode located at a same layer as the first capacitance electrode; 
 a second electrode located at a same layer as the second capacitance electrode; and 
 a dielectric layer located at a same layer as the first dielectric layer. 
 
     
     
       10. The electro-optical device according to  claim 1 , comprising:
 a plurality of inspecting elements respectively provided at a same layer as the temperature detecting element, the transistor, the resistance element, and the first capacitance element; and 
 a plurality of inspection terminals electrically connected to the inspecting elements. 
 
     
     
       11. An electronic device comprising the electro-optical device according to  claim 1 . 
     
     
       12. An electro-optical device comprising:
 a temperature detecting element; and 
 an electrostatic protection circuit includes: 
 a transistor including a gate electrode, a semiconductor layer, and a gate insulating film provided between the semiconductor layer and the gate electrode, the transistor being electrically connected in parallel to the temperature detecting element; 
 a first capacitance element including a first capacitance electrode, a second capacitance electrode, and a first dielectric layer provided between the first capacitance electrode and the second capacitance electrode, the first capacitance element being electrically connected to the transistor; and 
 a resistance element having one end electrically connected to the gate electrode and the first capacitance electrode and having another end electrically connected to the second capacitance electrode and a source-drain region on one side of the semiconductor layer, wherein 
 a thickness of the first dielectric layer is greater than a thickness of the gate insulating film. 
 
     
     
       13. An electro-optical device comprising:
 a temperature detecting element; 
 an electrostatic protection circuit; and 
 a display region, wherein 
 the electrostatic protection circuit including: 
 a transistor including a gate electrode, a semiconductor layer, and a gate insulating film provided between the semiconductor layer and the gate electrode, the transistor being electrically connected in parallel to the temperature detecting element, 
 a first capacitance element including a first capacitance electrode, a second capacitance electrode, and a first dielectric layer provided between the first capacitance electrode and the second capacitance electrode, the first capacitance element being electrically connected to the transistor, and 
 a resistance element having one end electrically connected to the gate electrode and the first capacitance electrode and having another end electrically connected to the second capacitance electrode and a source-drain region on one side of the semiconductor layer, 
 the display region including a plurality of pixels arrayed, 
 the plurality of pixels each including a retention capacitor and a pixel electrode, 
 the retention capacitor including: 
 a first electrode located at a same layer as the first capacitance electrode, 
 a second electrode located at a same layer as the second capacitance electrode, 
 a second dielectric layer located at a same layer as the first dielectric layer, 
 a third electrode electrically connected to the second electrode, 
 a fourth electrode electrically connected to the first electrode, and 
 a third dielectric layer provided between the third electrode and the fourth electrode.